Hydraulic fuel oil pump or the like



Jan. 27, 1970 J. H. PETERSEN 3,491,697

HYDRAULIC FUEL OIL PUMP OR THE LIKE Filed Nov. 27, 1967 2 Sheets-Sheet 1Jan; 27, 1970 J. H. PETERSEN 3,491,597

I HYDRAULIC FUEL OIL PUMP OR THE LIKE Filed Nov. 27, 1967 2 Sheets-Sheet2 United States Patent Int. (:1. F04c 1/04, 29/00 US. Cl. 103-126 9Claims ABSTRACT OF THE DISCLOSURE The invention relates to hydraulicpumps and particularly to the providing of a novel inlet chamberarrangement. The inlet chamber arrangement includes a centrally locatedinlet chamber to which a liquid such as oil is delivered throughradially extending passages. A tangentially extending passage extendstangentially relative to the inlet chamber and connects the inletchamher with the suction producing pumping elements. The tangentiallyextending passage causes the liquid in the inlet chamber to rotate andthereby provide certain advantage relating to the operation of the pump,including improved operation when the liquid supplied to the pump is ata relatively low level.

This invention relates to a hydraulic pump, especially a fuel oil pumphaving a suction port arranged in a vertical wall and a preliminarychamber preceding the suction port, the chamber being divided from thesuction chamber by a partition with inlet ports.

A problem encountered in hydraulic pumps, especially fuel oil pumps, isthe fact that air is separated in the suction chamber. When the liquidhas been completely sucked in, the pump will sometimes only convey air.This produces cavitation noises in the gears and orifice pressurevariations giving a pulsating flame; it also leads to the inadvertentoperation of the pressure-dependent cut-off valve, disturbs flamecontrol etc.

A hydraulic pump is known in which the suction port is arrangedcentrally and the inlet port consists of a slot extending in outwarddirection from the center, or of several bores situation on such aradial line. The inlet port is comparable to a passage the resistance ofwhich varies with the liquid level in the suction chamber. The lower theliquid level drops, the higher the resistance opposing the flow of theliquid, and the more air is drawn off along with the liquid.

With this pump, the radial slot must point in upward direction duringoperation. Furthermore, difficulties are experienced where aneccentrically arranged suction port is used. The desired admixture ofair and oil is the result of a pressure drop to which the oil issubjected. Quite apart from the desirability of avoiding pressure lossesof any kind, there is the further disadvantage of disturbing noiseswhich is also inherent in this mixing technique.

The present invention has for its object to draw off the air in a pumpof the type referred to with a smaller loss of pressure and provides fora pump operating independently of its working position so long as thepump shaft is substantially horizontal.

This object is achieved, according to the invention, in that thepreliminary chamber is axially symmetrical, the suction port is situatedclose to the periphery of the preliminary chamber and extendstangentially and ducts extending in outward direction from thepreliminary chamber connect the inlet ports with the chamber.

The liquid entering the preliminary chamber through 3,491,697 PatentedJan. 27, 1970 the submerged inlet ports is caused to rotate by thetangentially arranged suction port. Itv is immaterial whether thesuction port is in the lowest, highest or any other position. As soon asthe liquid level has dropped sufliciently far for the duct communicatingwith the air space through its inlet not to contain any more liquid, therevolving liquid pulls air from the point where the air space and theduct meet. This takes place without any considerable loss of pressure ornoise. The air is intimately mixed with the liquid because the mosthighly concentrated liquid is always present at the point where air isadmitted since, due to centrifugal force, the unmixed liquid is forcedupwards the periphery while the aerated liquid foam remains in thecentre region of the preliminary chamber. In this region the foamcushion also attenuates noise created by the pump shaft.

The above-mentioned ducts preferably extend radially and are uniformlydistributed over the circumference of the preliminary chamber.Advantageously, at least three ducts are provided. In this way, completepositional independence of the pump is achieved with a minimum of means.

Further, according to the invention, the longitudinal dimension of theinlet ports may be kept small in relation to their cross section. Thisincreases their operational independence on the viscosity of the liquid.It is sufficient for the size of the inlet port to be adapted to the suction capacity of the pump.

The positional independence and uniform air admixture provided for bythe invention are of particular importance for high-efiiciency pumpsbecause even small variations of the prescribed position can impair theefficiency of such pumps considerably. Thus, further ac cording to theinvention, the suction port in hydraulic gear pump leads to a suctionchamber, known per se, which charges the gears from both sides.

The low pressure losses of the pump of the invention make itparticularly suitable for constructions in which pressure losses havealready been reduced as far as possible. Therefore, still furtheraccording to the invention, the delivery chamber of the pump surroundsthe gears on both sides in known manner. This design also improves thehydraulic equilibrium of the gear.

A pump having the above-described characteristics is capable ofoperating with suction heads only 20 mm. below barometric pressure, i.e.up to about 710 mm. Hg. In this connection it is also important thatadequate charging can still be achieved with these high suction heads,due to the intimate admixture of liquid and air. This could not beachieved with less intense admixture.

As for the constructive design it is advantageous for the preliminarychamber, the ducts and the inlet ports to be provided in a cap attachedto the end of the pump.

It is also advantageous for a cover plate on the end face of the pump tocontain a shaft bearing as well as the suction port communicating withthe connection duct, and the suction and delivery chambers on one sideof the gears. An intermediate plate between the gears and the pumphousing may then be provided with the suction and delivery chambers onthe other side of the gears. At least one of these plates may beproduced by sintering, a very inexpensive process of manufacture.

The invention will now be described in further detail with reference toan embodiment thereof, illustrated by way of example in the drawings.

FIG. 1 shows an oil pump designed according to the invention in whichcover, diaphragm and filter have been removed;

FIG. 2 shows a longitudinal section along the line AA of FIG. 1;

FIG. 3 is a part-sectional view along the line BB of FIG. 1;

FIG. 4 is a part-sectional view along the line CC of FIG. 1.

The ducts 1 connect the pump intake with a distribution chamber 2arranged between a cover 3 and a filter 4. The oil entering the chamberis sucked into a suction chamber I through the filter 4, the suctionchamber being provided with a rubber diaphragm 5 which, together withthe air space behind it, is capable of equalizing the pressurefluctuations of the pump. From the suction chamber I, oil passes throughthe inlet ports 6 and radial ducts into an axially symmetricalpreliminary chamber II. The last-mentioned parts are provided in a cap 7which is mounted on the pump by means of bolts 8, a plate 9 beinginterposed. The bolts 8 also hold a cover plate 31, a gear plate 19 andan intermediate plate 32 to the pump housing 33. The inlet ports 6 arebores in a surface inclined by 45 to the axis of the shaft. Thereforethe projection of the port cross-section on the duct cross-section, andalso on the end face of cover plate 31, is smaller than the effectivecross-section of the port. The bores extend coaxially, so that the ports6 virtually have no longitudinal dimension which would make theirefficiency depend on viscosity.

In the cover plate 31 is provided aduct 11 which constitutes atangential continuation of the preliminary chamber 2 and forms a suctionport 36 on the end face of the cover plate 31. The duct 11 leads throughanother bore 12 into the inlet chamber of the pump which latter isformed by a toothed gear 16 and a toothed annulus 17. Behind the bore 12the oil stream divides. One part flows, through a connection duct 13 inthe cover plate, to a suction chamber 14 from where the suction toothgaps 15 are charged on one side. The remaining oil flows, through a bore18, and a connection duct 20, to another suction chamber 21 from wherethe suction tooth gaps 15 are charged on the other side. There the oilis conveyed to the delivery side. From the delivery tooth gaps 22 theoil is discharged in two part-streams through the ducts 23, 24. Thegears are hydraulically relieved due to the fact that oil pressure isthe same on both sides. The oil passes through connection ducts 25, 26into collecting ducts 27, 28 of the gear plate 19 from where it flowsthrough a bore 29 passing through the gear plate 19, the intermediateplate 32 and the housing 33 into a connection duct and to the deliveryvalve of the pump.

In the cap 7 are provided the preliminary chamber II, the three ducts 10and the inlet ports 6. The cover plate 31 supports the pump shaft 34; italso contains the oil ducts 11, 12, 13, 14, 24 and 25. In theintermediate plate 32 are provided the chambers 20, 21, 23 and 25.

When oil is sucked in during operation through the tangential duct 11,the oil in the preliminary chamber II begins to rotate. When the levelof the oil has dropped below the point 35, the revolving oil takes alongthe air induced through the upper inlet port 6 and the upper radial duct10. This air is intimately mixed with the oil, so that it cannot do anyharm while being conveyed through the pump. Due to centrifugal force, alighter air/ oil mixture forms in the centre of the vortex, so that avery concentrated volume of oil becomes available in the region of themixing point 35. Also the suction port 36 is situated in this region ofincreased oil concentration. The oil vortex is fed with fresh oil frombelow and can thus maintain the above-described condition. In this wayit becomes possible quickly and reliably to suck off surplus air, with aminimum loss of pressure and without appreciable noise. Due to theintimate admixture with oil, no disturbance in subsequent parts of thepump system needs to be anticipated.

It is obvious, furthermore, that it is immaterial for the operation of apump of this design whether the pump assumes the position illustrated inthe drawing or is turned about its horizontal axis by any desiredamount, for several inlet ports 6 and ducts 10 are available for theentry of oil and air, and the tangential suction duct 11 is capable ofconveying the oil and initiating its rotation in any angular position.

I claim:

1. A hydraulic pump comprising, a casing, a horizontally extending shaftrotatably supported by said casing, pumping means attached to saidshaft, a plate member attached to said casing adjacent said pumpingmeans, a cap member attached to said plate member on the opposite sidethereof from said pumping means, said cap member forming an inletchamber having a centrally disposed portion and a plurality of radiallyextending duct portions, each of said duct portions having an inlet portat its radial extremity, a suction passage formed in said plate memberproviding fluid communication between said inlet chamber and saidpumping means, said suction passage extending tangentially relative tothe periphery of said centrally disposed portion of said inlet chamber.

2. A hydraulic pump according to claim 1 characterized by said ductportions extending radially outwardly and being symmetrically arranged.

3. A hydraulic pump according to claim 1 characterized by there being atleast three of said duct portions.

4. A hydraulic pump according to claim 1 characterized by the plane ofeach of said inlet ports being at an angle of approximately 45 relativeto the longitudinal axis of the pump.

5. A hydraulic pump according to claim 1 characterized by fluid inletpassages on opposite sides of said pumping means for admitting a fluidto both sides of said pumping means, said fluid inlet passages being influid communication with said suction passage.

6. A hydraulic pump according to claim 5 characterized by fluid outletpassages on opposite sides of said pumping means for receiving fluiddischarged from both sides of said pumping means.

7. A hydraulic pump according to claim 1 characterized by said capmember having the form of a shell-like gap, and means for attaching saidcap to said plate mem- -8. A hydraulic pump according to claim 6characterized by said plate member having the form of a cover plate,said shaft having one end thereof rotatably supported in said coverplate, and said cover plate having a portion of said fluid inlet andoutlet passages formed therein.

9. A hydraulic pump according to claim 8 characterized by a side plateadjacent said pumping means on the opposite side thereof from said platemember, said side plate having a portion of said inlet and outletpassages formed therein.

References Cited UNITED STATES PATENTS 2,751,847 6/ 1956 Erikson.2,775,206 12/ 1956 Connelly. 2,966,118 12/ 1960 McAlvay. 3,162,12912/1964 Erikson. 3,312,177 4/1967 Eckerle et al. 3,343,494 9/1967Erikson et al.

ROBERT W. WALKER, Primary Examiner W. I. GOODLIN, Assistant Examiner US.Cl. X.R. 230207

